A light emitting diode that is low price than a laser diode has attracted attention as a light source for plastic optical fibers (POF). There becomes necessary a vertical resonator type light emitting diode having a resonator that causes light to resonate, since the conventional light emitting diode is unsatisfactory to achieve higher output power and more rapid responses.
A vertical resonator type light emitting diode has a structure that a double-heterostructure containing an active layer is sandwiched from its upper and lower sides between reflector layers to cause light from the active layer to resonate, constituting a vertical resonator whereby light emitted from the active layer is caused to resonate in directions vertical to the active layer. The reflector layer at each side comprise multiple pairs of Bragg reflector layers having high and low refractive index films alternately formed to increase their reflectance. The reflectances of the reflector layers are such that the reflectance of the reflector layer on the light emitting side is lower than that of the other side so that light emission at the active layer can be selectively emitted from the reflector layer.
Such a vertical resonator type light emitting diode is deemed to be used in a high temperature region of 100° C., and a vertical resonator type light emitting diode which has a small temperature dependence of emission output power has been required. Patent Reference 1 discloses a vertical resonator type light emitting diode in which the reflector layer at its light emitting side, namely at its front side has a plurality of reflection band characteristics to prevent its emission output power from falling in the high temperature region.
Patent Reference 1: Japanese laid open patent application, JP 2003-332615 A